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Biomedical subjects

T Imamura

Publications and source records attributed to T Imamura.

At least 325 records · Page 18Linked to original sources
PubMed1995

Rhythmic Cl- current and physiological roles of the intestinal c-kit-positive cells.

Chronic injection of an anti-c-KIT receptor tyrosine kinase monoclonal antibody (ACK2) results in the disruption of the normal motility patterns of young BALB/c mice intestine. This effect is accompanied by a drastic decrease in the number of intestinal c-kit-expressing (c-kit+) cells when studied immunohistochemically with the fluorescence-labelled antibody. In order to clarify the mechanism underlying the ACK2 action and the physiological roles of intestinal c-kit+ cells, we studied the excitability of intestinal c-kit+ cells in primary culture by use of the nystatin perforated-patch-clamp technique. Under voltage-clamp at -40 mV, the majority of c-kit+ cells tested (59/70) elicited rhythmic current waves with an amplitude and frequency of 263 +/- 24 pA and 2.30 +/- 0.25 cycles/min (mean +/- SEM), respectively. Intracellular perfusion of the c-kit+ cells with ethylenebis (okonitrilo) tetraacetate (EGTA) as well as a nominally Ca(2+)-free external solution or low holding voltage (< -60 mV) prevented the rhythmic current. The reversal potential of the rhythmic current was close to the equilibrium potential for Cl-(ECl). Moreover the rhythmic current was depressed by a Cl- channel blocker, 4-acetoamido-4-isothiocyanat-ostilbene-2,2'-disulphoni c acid (SITS). The smooth muscle cells freshly dissociated from the same intestinal specimen revealed a Ca(2+)-activated K+ current, as has been described in a variety of smooth muscle cells. Cultured smooth muscle cells from the ileum preparation lacked neither the Ca(2+)-activated K+ nor rhythmic Cl- currents. Smooth muscle cells freshly dissociated from the same ileum preparation and those in culture showed no immunoreactivity with the labelled ACK2, which was consistent with our previous in situ study. Results provided direct evidence that the intestinal c-kit+ cells, but not the smooth muscle cells, possess a rhythmic Cl- current oscillation, suggesting their participation in pacemaker activity for the peristaltic gut movement.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1995

Distribution of Tn antigen recognized by an anti-Tn monoclonal antibody (MLS128) in normal and malignant tissues of the digestive tract.

Alterations in the normal glycosylation process are often associated with oncogenic transformation. Using an anti-Tn monoclonal antibody, MLS128, we have investigated the immunohistochemical localization of Tn antigen in normal and malignant tissues of the digestive tract. In normal tissues, MLS128 was immunoreactive with the squamous epithelium of the esophagus and was weakly reactive with the columnar epithelia of the stomach, duodenum, colon, bile duct and pancreatic duct. In malignant tissues, positive immunostaining was detected with high frequency (75%-100%) in carcinomas of the esophagus, stomach colon, biliary tract and pancreas, whereas 2 of 11 (18%) hepatocellular carcinomas were positive. Tn antigen was detected in the upper two-thirds of the normal squamous epithelium, and was often detected in squamous cell carcinomas with cancer pearls (keratinization). These results suggest that the expression of Tn antigen is related to the differentiation of squamous epithelium, or to keratinization. In normal columnar epithelial cells. Tn antigen was localized mainly to the Golgi area. This intracellular localization was preserved in well-differentiated papillary adenocarcinomas of the colon, but was lost in most cases of tubular adenocarcinomas.

Adenocarcinoma↗
PubMed1995

Interaction of indole and tryptophan derivatives with sodium dodecyl sulfate micelles measured with ultraviolet absorption and fluorescence quenching.

The distribution of indole and tryptophan derivatives between sodium dodecyl sulfate (SDS) micellar and aqueous phases was analyzed using conventional methods of ultraviolet (UV) absorption spectroscopy and measurement of fluorescence quenching by succinimide. On the assumption of a simple pseudo-phase equilibrium between both phases the distribution coefficient was easily obtained by the measurement of the ratio Rpv of the absorbance intensity in the peak to that in the valley of the UV spectra or the fluorescence quenching constant Ksv. The possibilities and limitations of utilizing the ratio of the collisional quenching constant estimating from the Ksv value in the micellar phase to that in the aqueous phase for a measure of polarity of the microenvironment around the tryptophan derivatives in the SDS micelle is discussed in comparison with the Rpv values for the UV spectra. The indole ring in the derivatives in the SDS micelle is localized near or on the micelle-water interface with its imino group directed toward the aqueous phase. Thus it can serve as a feasible model for interpreting the distribution coefficients and Rpv values obtained for the various indole and tryptophan derivatives.

Indoles↗
PubMed1995

Immunohistochemical staining for type IV collagen and laminin in the stroma of human pancreatic cancer.

Fourteen human pancreatic cancer, six normal pancreatic, and four alcoholic chronic pancreatitis tissue samples were examined by immunohistochemistry with antitype IV collagen and antilaminin monoclonal antibodies (MAb). The basement membranes of acinar, ductal, and endothelial cells from all of the normal pancreatic and alcoholic chronic pancreatitis tissue samples were continuously immunostained, but the stroma was negatively immunostained by both antibodies. On the other hand, all 14 pancreatic cancer tissues showed irregular immunostaining on the basement membranes surrounding cancer cells, and positive fibrillar immunostaining for type IV collagen in the stroma of the carcinomatous parenchyma. Six of the 14 pancreatic cancer tissue samples also showed positive immunostaining for laminin in the stroma. The stromal type IV collagen with or without laminin in human pancreatic cancer tissues may have originated from basement membranes degraded through cancer invasion and proliferation.

Adult↗
PubMed1995

Amplification and analysis of promoter region of insulin receptor gene in a patient with leprechaunism associated with severe insulin resistance.

A patient with leprechaunism associated with severe insulin resistance was studied to identify the molecular and genetic basis for insulin resistance. Insulin binding and surface labeling of transformed lymphocytes prepared from the patient showed a significantly decreased insulin receptor number on the cell surface. Southern blot analysis of the insulin receptor gene showed no evidence of large insertions or deletions. Furthermore, direct sequencing of all 22 exons and exon-intron junctions of the insulin receptor gene failed to show any missense mutations, nonsense mutations, or mutations at exon-intron junctions. However, Northern blot analysis indicated significantly decreased insulin receptor mRNA expression in the patient's cells. Moreover, restriction endonuclease digestion of the amplified cDNA suggested that the expression levels of one allele were less efficient than the other. These findings suggested that the regulatory region of the insulin receptor gene might have abnormalities. Therefore, we examined the 5' flanking region of the insulin receptor gene. Southern blot analysis showed no major deletions or insertions between positions -1,823 and -2 relative to the translation initiation site. A 5' flanking region of the insulin receptor gene spanning positions -881 approximately +7 was amplified by polymerase chain reaction (PCR) and introduced into a reporter plasmid carrying the human growth hormone (hGH) gene. The nucleotide sequence of the amplified fragment showed two polymorphic sites at positions -603 and -500 in the patient, as well as in normal subjects. No other abnormal sequence was found in the patient. Promoter activity measured by hGH expression in transfected mouse L cells was not influenced by the polymorphism at position -603 located in a cluster of GC boxes.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1995

Malignant trophoblastic neoplasms with different modes of origin.

The genetic origin of 24 trophoblastic neoplasms was determined using PCR polymorphisms. Based on pregnancy history, these tumors included nine postmolar trophoblastic tumors, 12 tumors preceded by live birth or abortion, and three nongestational tumors. Androgenetic origin was defined in eight post-molar trophoblastic tumors, and the remaining one might have arisen from a normal fertilization. Six tumors retained genetic features carried by the homozygous complete mole. Two tumors showed PCR polymorphism compatible with that of the heterozygous complete mole. All 12 tumors in the second class had alleles of both paternal and maternal contribution. However, discordance of sex between the antecedent pregnancy product and the tumor was recognized in three choriocarcinomas. The absence of paternal contribution suggested a parthenogenetic origin of three nongestational choriocarcinomas. The findings that PCR polymorphisms were either homozygous in certain loci or heterozygous in others may mean that the tumor was derived from a germ cell after meiosis I. As a result, at least three subtypes with different modes of origin were demonstrated in the 24 trophoblastic tumors. These findings underscore the importance of precise genetic marker analyses in a large series to clearly identify clinical and biologic characteristics of each subset of tumors.

Base Sequence↗
PubMed1995

The role of p53 inactivation in human cervical cell carcinoma development.

We investigated the association between human papillomavirus (HPV) infection and p53 gene mutation in 47 primary uterine cervical cancers. HPV DNA sequences were present in 43 cancers (91.5%), and one of these cancers contained a p53 gene mutation. In addition, one of the remaining four HPV-negative cancers also contained a p53 gene mutation. As a result, p53 inactivation corresponded to the development of 44 of the primary uterine cervical cancers studied (93.6%). We obtained both primary and recurrent tumours from four cases. In two of these cases, the HPV genomes that were present in an episomal state in the primary tumours were observed to have disappeared in the recurrent tumours. One of these recurrent tumours also contained a p53 gene mutation, which suggested the possibility that p53 inactivation was required in order to maintain the aggressive behaviour in this cancer either by an HPV infection or by a p53 gene mutation. No MDM2 gene amplification was observed in the tumours that carried neither HPV DNAs nor p53 gene mutations.

Adenocarcinoma↗
PubMed1995

Transovarian transmission of a foreign gene in the silkworm, Bombyx mori, by Autographa californica nuclear polyhedrosis virus.

We introduced a firefly luciferase gene, expressed under control of Drosophila heat shock protein gene promoter, into Autographa californica nuclear polyhedrosis virus (AcNPV). When the 5th instar larvae of the silkworm, Bombyx mori, were inoculated with the recombinant virus, luciferase activities were detected in the virus-infected larvae and pupae, and in the newly hatched larvae of the next generation. PCR amplification and Southern blot hybridization analysis demonstrated that the luciferase gene was transmitted through at least the F2 generation. In addition, the V-cathepsin gene, encoding a cysteine protease of AcNPV, was also detected in the DNA of all individuals of the F2 generation. These results show that AcNPV can be utilized as vector for the transovarian transmission of foreign genes in the silkworm.

Animals↗
PubMed1995

Quantitative analysis of collagen and collagen subtypes I, III, and V in human pancreatic cancer, tumor-associated chronic pancreatitis, and alcoholic chronic pancreatitis.

The collagen content in human pancreatic cancer tissue, tissue of tumor-associated chronic pancreatitis (TACP), and normal pancreatic tissue was determined in 14 patients with pancreatic cancer by measuring the amount of 4-hydroxyproline. Four patients with alcoholic chronic pancreatitis (AlCP) were also analyzed. The mean collagen content in both pancreatic cancer tissue and TACP tissue was approximately threefold higher than in normal pancreatic tissue. Cyanogen bromide peptides of type I, III, and V collagens from invasive ductal carcinomatous tissue of the pancreas and from TACP tissue of eight patients were analyzed sequentially using high-performance liquid chromatography with ion-exchange and gel-permeation columns. No difference in the proportion of type I, III, and V collagens was detected between pancreatic cancer tissue and TACP tissue. The mean collagen content in AlCP tissue was significantly lower than that in TACP tissue, but no difference in the proportion of type I, III, and V collagens was detected between these two tissues. These results indicate a similar quantity and distribution pattern of fibrillar collagen in human pancreatic cancer and TACP.

Alcoholism↗
PubMed1995

Isolation and characterization of bile acid 7-dehydroxylating bacteria from human feces.

Methods for isolation of fecal 7 alpha-dehydroxylating bacteria are presented. A total of 219 strains were isolated from feces of healthy humans, and their ability to 7-dehydroxylate cholic, chenodeoxycholic, and ursodeoxycholic acids were examined. Of all the isolates, 14 strains were found to be capable of eliminating the hydroxy group at C-7 alpha and/or C-7 beta. All the isolates were strictly anaerobic, Gram-positive rods. Thirteen isolates were non-sporeforming bacteria showing certain saccharolytic properties with the production of acid and gas from dextrose, and were catalase-positive but indole-, lecithinase-, urease- and oxidase-negative. Based on the data available at present, it was concluded that they could be regarded as members of the genus Eubacterium. One strain, however was identified as Clostridium sordellii. The isolated strains capable of 7 alpha-dehydroxylating cholic acid and chenodeoxycholic acid were also able to oxidize the hydroxy group at C-7 alpha. Nine strains (10, 12, 36S, M-2, M-17, M-18, Y-98, Y-1112, and Y-1113) of the 7 alpha-dehydroxylating bacteria were confirmed to have 7 beta-dehydroxylation ability, but five strains (O-51, O-52, O-71, O-72, and Y-67) could not transform ursodeoxycholic acid to lithocholic acid.

Adult↗
PubMed1995

Intravenous leiomyomatosis: three case-reports.

In the 3 cases of intravenous leiomyomatosis presented here, the retroperitoneal, pelvic, and vaginal veins were completely removed. Two of the cases were diagnosed by a gynecologist at surgery, and 1 was diagnosed by the pathologist performing a histological examination on excised tissue. These 3 cases were asymptomatic in spite of the intravenous invasive leiomyomatosis.

Adult↗
PubMed1995

Effect of free and vesicle-bound cysteine proteinases of Porphyromonas gingivalis on plasma clot formation: implications for bleeding tendency at periodontitis sites.

Infection by Porphyromonas gingivalis is strongly associated with adult periodontitis, with proteinases from this bacterium now considered to be important virulence factors. In order to investigate possible pathological functions of these enzymes, we examined the effect of both free and vesicle-bound forms of the two major cysteine proteinases (gingipains) of P. gingivalis on plasma clot formation by using thrombin time (TT) measurements. Both Lys-gingipain (gingipain-K) and Arg-gingipain (gingipain-R) prolonged plasma TT in a dose- and time-dependent manner, and this was also found with vesicles which are the biological carriers of P. gingivalis proteinases. The increase in plasma TT by vesicles could be completely reversed by treatment with nonspecific cysteine proteinase inhibitors but only partially by compounds selective for either gingipain-K or gingipain-R. Preincubation of vesicles with a gingipain-K-specific inhibitor (z-FK-ck) reduced plasma TT more than a gingipain-R-specific inhibitor (leupeptin), suggesting that under physiological conditions gingipain-K was more effective in fibrinogen destruction. Each purified enzyme also markedly increased fibrinogen TT, gingipain-R being fourfold more potent than gingipain-K. However, in plasma, gingipain-R was ineffective because of the inhibitory effect of albumin. These results imply that cysteine proteinases, especially gingipain-K, abrogate the clotting potential of fibrinogen and, therefore, may contribute to the bleeding tendency and to persistent inflammation in periodontitis sites infected with P. gingivalis.

Adhesins, Bacterial↗
PubMed1995

Dependence of vascular permeability enhancement on cysteine proteinases in vesicles of Porphyromonas gingivalis.

Infection with Porphyromonas gingivalis is strongly associated with adult periodontitis, and proteinases are considered to be important virulent factors of the bacterium. In order to investigate the function of proteinases in disease development we examined vesicles, a biological carrier of these enzymes, for the generation of vascular permeability enhancement (VPE) activity, believed to correlate with the exudation of gingival crevicular fluid. The vesicles generated VPE activity from human plasma in a dose-dependent manner which could be inhibited 90% by antipain, a specific inhibitor of the Arg-specific cysteine proteinases (Arg-gingipains [RGPs] from P. gingivalis. Incubation of vesicles with high-molecular-weight-kininogen (HMWK)-deficient plasma did not result in VPE activity. On this basis, RGPs associated with vesicles were assumed to be responsible for most of the VPE activity generation via plasma prekallikrein activation and subsequent bradykinin production. The secondary pathway for VPE activity production was dependent on the direct release of bradykinin from HMWK by the concerted action of RGP and a Lys-specific cysteine proteinase (Lys-gingipain [KGP]), also associated with vesicles. These results indicate that RGP and KGP are biologically important VPE factors acting either via prekallikrein activation (RGP) and/or HMWK cleavage (RGP and KGP) to release BK and, thereby, contributing to the production of gingival crevicular fluid at periodontal sites infected with P. gingivalis.

Adhesins, Bacterial↗
PubMed1995

Plasmacytoma of the testis.

Extramedullary plasmacytomas of the testes are extremely rare tumors, especially when occurring in the absence of precocious or concurrent diagnosis of multiple myeloma. This is a case report of an 83-year-old man with a solitary plasmacytoma of the left testis. Immunoperoxidase studies, performed on histologic specimens after radical orchiectomy, showed a monoclonal staining of intracellular immunoglobulin for IgG-lambda type. He has been well for more than 14 months with no evidence of local recurrence or multiple myeloma.

Aged↗
PubMed1995

HFA-134a (1,1,1,2-tetrafluoroethane); lack of oncogenicity in rodents after inhalation.

1. Groups of 60 male and 60 female B6C3F1 mice or HanIbm Wistar rats were exposed to HFA-134a using snout-only inhalation exposure techniques for periods of one hour daily for at least 104 weeks. HFA-134a was delivered directly from cylinders at vapour concentrations of 2500, 15,000 and 75,000ppm for mice and from metered-dose inhalers at vapour concentrations of 2500, 10,000 and 50,000ppm for rats. 2. Intended dosages were achieved. 3. Evidence of absorption was found at each dose level and was dose related. 4. Neither species suffered treatment related effects on survival, clinical signs, body weights, haematology nor on the type, incidence, site or severity of gross lesions. 5. There was no effect of treatment on the type, incidence, site or severity of neoplasms in mice or rats. 6. There were no non-neoplastic findings related to treatment in mice. 7. HFA-134a was considered not to be oncogenic and to provide a safe alternative to chlorofluorocarbons for use in pharmaceutical metered-dose inhalers.

Absorption↗
PubMed1995

[Age-related changes in the retina of WBN/Kob rats--a pathological study].

Male rats of the WBN/Kob strain, which are known to spontaneously develop diabetes with aging, were examined for histopathological changes in the retina. Five rats (10 eyes) each of WBN/Kob and Wistar/ST as a control were used, and the thickness of the retinal layers, both the central region and the peripheral region of the retina, were measured on weeks 1, 2, 3, 5, 9, 13, 17, 23, 27, 36, 45, 54, 67 and 80 after birth. The rod and cone cell layer in WBN/Kob rats was under-grown, and its thickness decreased 71.7% in the central zone and 59.3% in the peripheral zone of the retina compared with that of the control. In the central and peripheral retina, the rod and cone cell layer, outer nuclear layer and outer plexiform layer, as well as the inner plexiform layer in the central retina, gradually decreased in thickness from 5-45 weeks of age. In the central and peripheral parts of the retina, the number of nuclei decreased in accordance with the thinning of the nuclear layer. The thinned layers showed only cell loss. The rod and cone cell layer of the peripheral retina was thinner than that of the central retina. We obtained the following findings in the retina of male WBN/Kob rats. First, the rod and cone cell layer is undergrown compared with that of the control. Second, the first change occurred in the rod and cone cell layer. Third, the thinning of the rod and cone cell layer appeared at 5 weeks of age, and thinning with aging was slow. And finally, the thinning of the peripheral retina was more severe than that of the central retina. From the above findings, it seems that retinal changes in WBN/Kob rats are similar to the retinal degeneration of rds mice (retinal degeneration slow mice) and that WBN/Kob rats provide a useful animal model for human retinopathy.

Aging↗